1. Field of the Invention
The present invention relates to an optical-position adjusting device for an optical unit, by which a position of a lens barrel relative to a cylindrical member, in which the lens barrel is housed, is adjusted.
2. Description of the Related Art
Conventionally, there is known an optical device provided with an optical unit in which a lens barrel is moved along the central axis thereof by rotating a cylindrical member, so that a focusing operation of the optical system provided in the lens barrel is performed. Namely, due to a movement-conversion mechanism assembled between the cylindrical member and the lens barrel, a rotation of the cylindrical member is converted to a linear movement of the lens barrel along the central axis of the cylindrical member. The linear movement is the focusing movement of the optical system provided in the lens barrel. For performing the focusing movement properly, it is necessary to position the lens barrel relative to the cylindrical member at a predetermined correct position.
Accordingly, parts forming the optical unit are manufactured with a predetermined accuracy, and after assembling the optical unit, the lens barrel is positioned relative to the cylindrical member at a predetermined correct position. Actually, however, each of the parts of the optical unit has a manufacturing error, and an assembling error may occur in the optical unit. Thus, an optical-position adjusting device is assembled in the optical unit so that the lens barrel is positioned relative to the cylindrical member after the assembling process.
Generally, it is desirable for the portable optical device to be compact or reduced in size, and thus, an optical unit mounted in the portable optical device is required to be as compact as possible. Further, the optical unit has to be adjusted in accordance with a positional offset occurring because of change in operating conditions.
Therefore, an object of the present invention is to provide an optical-position adjusting device, which is miniaturized as much as possible, and by which an optical-position adjustment is easily performed.
According to the present invention, there is provided an optical-position adjusting device for an optical unit, comprising a cylindrical member, a support member, a lens barrel, a movement-conversion mechanism, a ring, and a fixing member.
The cylindrical member is rotatable about the axis thereof. The support member rotatably supports the cylindrical member. The lens barrel is disposed in the cylindrical member and linearly movable along the central axis of the cylindrical member. The movement-conversion mechanism converts a rotational movement of the cylindrical member into a linear movement of the lens barrel. The ring is fit on the lens barrel in such a manner that the lens barrel can be moved along the central axis thereof. The ring is non-rotatable relative to the lens barrel. The fixing member is provided for fixing the ring to the support member in such a manner that the ring can be released from the support member.
Due to this construction, when the fixing member is released from the support member, the ring becomes rotatable. The ring is then rotated, so that the lens barrel is rotated and linearly moved along the central axis of the cylindrical member due to the movement-conversion mechanism. Thus, when the ring is fixed to the support member through the fixing member after the lens barrel is positioned exactly at a predetermined position relative to the cylindrical member, the positioning process of the lens barrel to the cylindrical member is completed.
The ring may comprise teeth formed on at least a part of an outer periphery of the ring, and a key element that is slidably engaged with a key groove formed on an outer surface of the lens barrel and extended in the longitudinal direction thereof. In this case, the fixing member has a gear that is meshed with the teeth of the ring and is fixed on the support member through a screw, and the ring is rotatable when the screw is loosened, and is fixed relative to the support member when the screw is tightened.
Preferably, the lens barrel has an end portion projecting from the cylindrical member, and the ring is fit on the end portion.
The support member may be formed with a relief groove extending along the central axis of the lens barrel, to avoid an interference between said fixing member and the support member.
Further, according to the present invention, there is provided a binocular telescope with a photographing function, comprising an inner frame, a pair of telescopic optical systems, a rotary wheel, a focusing mechanism, a cylindrical member, a support member, a lens barrel, a movement-conversion mechanism, a ring, and a fixing member.
The pair of telescopic optical systems has a stationary part fixed on the inner frame, and a movable part movable relative to the stationary part, so that the telescopic optical systems focus on a subject. The rotary wheel is provided for focusing the pair of telescopic optical systems. The focusing mechanism converts a rotational movement of the rotary wheel into a relative movement of the movable part relative to the stationary part. The cylindrical member is rotatable about the axis thereof. The support member is a part of the inner frame to rotatably support the cylindrical member. The lens barrel is disposed in the cylindrical member and linearly movable along the central axis of the cylindrical member, and houses a photographing optical system. The movement-conversion mechanism converts a rotational movement of the cylindrical member into a linear movement of the lens barrel to focus the photographing optical system. The ring is fit on the lens barrel in such a manner that the lens barrel can be moved along the central axis thereof. The ring is non-rotatable relative to the lens barrel. The fixing member is provided for fixing the ring to the support member in such a manner that the ring can be released from the support member.